A reactor is used in various applications including a driving system of a hybrid vehicle and an electric vehicle and the like. For example, as a reactor used for an onboard booster circuit, the one in which a pair of coils are wound around a bobbin made of resin disposed around a core is used in many cases.
In this type of reactors, if a high current is continuously flown to the coil, the coil is overheated and electric characteristics of the reactor decreases.
Therefore, an internal temperature is detected by a temperature sensor such as a thermistor, and conduction control is carried out so that the coil is not heated to a certain temperature or higher.